The study will examine the role of the following substances in relation to spontaneous abortion and fetal defect: alcohol, aspirin, heroin, marijuana, methadone, and tranquillizers. Two approaches will be taken. First, substances which are associated with spontaneous abortion will be identified through a comparison of the karyotypic and morphologic characteristics of the conceptions of exposed and unexposed parents. For each substance, the duration of exposure, the timing in relation to conception and the parent involved will be considered. The proposed study will extend the fieldwork, modify the interview, and refine the analysis of a prior epidemiological study.